1. Field of the Invention
This invention generally relates to an arrangement for and a method of establishing a logical relationship among peripherals in a wireless local area network, the peripherals being in communication with one another and with a system manager for managing the network by a low power, wireless, radio frequency, communications protocol.
2. Description of the Related Art
Logical networks or virtual local area networks (LANs) are becoming increasingly important as LANs are interconnected with metropolitan or global networks which, in turn, have their own local area networks. In a physical local area network, all of the hosts in the LAN are physically connected to the same LAN cable or wire pair. In a logical network, a particular set of arbitrary hosts throughout the entire network is selected as a closed group. That is, hosts physically located in different local subnetworks may be logically connected as a single virtual LAN. This closed group is administered as a logical LAN independent of other groups of hosts. In the Internet, these logical LANs are referred to as logical IP subnets (LIS). Typically, a LIS requires manual configuration of each host by LAN administrators of each LAN where a logical LAN host is physically located.
U.S. Pat. No. 5,751,967 describes methods and apparatus for automatic configuration of switched networks implementing virtual local area networks (VLANs). Standard networking devices such as xe2x80x9cconcentratorsxe2x80x9d or xe2x80x9chubsxe2x80x9d which have a plurality of ports for connecting to different types of network cables such as fiber optic cable, unshielded twisted pair cable and shielded twisted pair cable may be used in conjunction with software for creating the virtual network. Typically, such software code is executed at run-time in a single networking device and interacts with software for communication in other networking devices, although such features may be implemented in any variety of dedicated hardware devices in a networking device including, but not limited to, discrete logic circuits, large scale integrated circuits (VLSIs) or application-specific integrated circuits (ASICs).
The switched networking system may include a variety of technologies, for example, those employing either configuration-switched, frame-switched or cell-switched devices, any one or more of which can support the creation of VLANs.
Virtual auto-configuration (VAC) is a management tool implemented as a series of executable routines which are operative within a single device (e.g., NCE) in a switched networking system. Active within the device is a process known as the virtual auto-configuration daemon (VAC deamon) process which is responsible for managing all the VLAN devices in the switched inter-network via communication with software process resident in those devices. A virtual auto-configuration manager interacts with the daemon process wherein the network manager may set up various virtual local area networks in the switched inter-network by defining xe2x80x9cpoliciesxe2x80x9d within manager processes. Policies are broadly defined as rules which specify how end-stations within the switched network should be grouped into VLANs. Policies are maintained using a policy configuration user interface which is resident within the VAC manager.
For example, a network manager may specify that all end-stations having predetermined media access control (MAC) addressed within a specified range are members of the same VLAN. Other policies may be defined based on any polled network data. Policies may be defined in any number of ways including, but not limited to, the use of a graphical user interface (GUI) using well-known techniques for creating tables with values/strings and other data times for populating tables specifying the policies. With communication with the VAC daemon process, a networks management station may also present a graphical display to the network manager of the virtual networks in the system. This may be done using any number of techniques, for example, a text list mapping VLANs to names or a graphical user interface displaying the physical configuration of the network (topology) and end-stations.
Such logical networks comprise, among other things, a plurality of components, devices, and other peripherals that cooperate and interact in a logical or working relationship. There may be multiples of each such peripheral, in which case, the identity of each such peripheral is critical for proper network operation.
One example of such multiple peripheral networks is an electro-optical reader for reading indicia such as bar code symbols appearing on a label or on a surface of an article. In its simplest form, the symbol itself is a coded pattern of indicia comprised of, for example, a series of bars of various widths spaced apart from one another to bound spaces of various widths, the bars and spaces having different light reflecting characteristics.
The scanning of bar code patterns has become more complex as bar code patterns have become both more complex and more compact. The typical bar code pattern includes lines and spaces of different widths extending in an x direction, and can be scanned by one or more linear scans in the x direction. Moreover, because the direction of the scan is not always precisely aligned with the direction of the bar code pattern, more complex omnidirectional scanning patterns are sometimes used, wherein consecutive scan lines are angularly displaced relative to one another to form a complex omnidirectional scanning pattern. Two dimensional (2D) bar code patterns (Code 49) have also been introduced wherein, in addition to a typical bar code pattern having lines and spaces of varying widths along an x direction, typical bar code patterns are stacked one upon the other in the y direction to form the 2D bar code pattern. Accordingly, scanning of a 2D bar code pattern is more complex, and requires a raster type of scan wherein consecutive x direction scans are displaced in the y direction by the spacing between stacked rows of the 2D bar code pattern to form a raster scan.
The readers and scanning systems electro-optically transform the graphic indicia into electrical signals, which are decoded into alphanumerical characters that are intended to be descriptive of the article or some characteristic thereof. Such characters are typically represented in digital form and utilized as an input to a data processing system for applications in point-of-sale processing, inventory control, and the like. Scanning systems of this general type have been disclosed, for example, in U.S. Pat. Nos. 4,251,798; 4,369,361; 4,387,297; 4,409,470; 4,760,248; and 4,896,026, all of which have been commonly assigned to the same assignee as the present application.
As disclosed in some of the above patents, one embodiment of such a scanning system resides, inter alia, in a portable laser scanner which is grasped and hand-held by a user, which is designed to allow the user to aim the scanner, and more particularly, a light beam emanating therefrom, at a target bar code symbol to be read.
In prior art bar code scanners, the light source in a laser scanner is typically a gas laser or semiconductor laser. The use of a semiconductor device such as a laser diode as the light source in scanning systems is especially desirable because of its small size, low cost and low power requirements. The laser beam is optically modified, typically by a lens, to form a beam spot of a certain size at the target distance. It is preferred that the beam spot size at the target distance be approximately the same as the minimum width between regions of different light reflectivity, i.e., the bars and spaces of the symbol.
Bar code symbols are formed from bars or elements that are typically rectangular in shape with a variety of possible widths. The specific arrangement of elements defines the character represented according to a set of rules and definitions specified by the code or symbology used. The relative size of the bars and spaces is determined by the type of coding used, as is the actual size of the bars and spaces. The number of characters per inch represented by the bar code symbol is referred to as the density of the symbol. To encode a desired sequence of characters, a collection of element arrangements are concatenated together to form the complete bar code symbol, with each character of the message being represented by its own corresponding group of elements. In some symbologies a unique xe2x80x9cstartxe2x80x9d and xe2x80x9cstopxe2x80x9d character is used to indicate where the bar code begins and ends. A number of different bar code symbologies exist. These symbologies include UPC/EAN, Code 39, Code 128, Codabar, and Interleaved 2 of 5.
For the purpose of this discussion, characters recognized and defined by a symbology shall be referred to as legitimate characters, while characters not recognized and defined by that symbology are referred to as illegitimate characters. Thus, an arrangement of elements not decodable by a given symbology corresponds to an illegitimate character(s) for that symbology.
In order to increase the amount of data that can be represented or stored on a given amount of surface area, several new bar code symbologies have recently been developed. One of these new code standards, Code 49, introduces a xe2x80x9ctwo-dimensionalxe2x80x9d concept by stacking rows of characters vertically instead of extending the bars horizontally. That is, there are several rows of bar and space patterns, instead of only one row. The structure of Code 49 is described in U.S. Pat. No. 4,794,239, which is hereby incorporated by reference.
A one-dimensional single-line scan, as ordinarily provided by hand-held readers, has disadvantages in reading these two-dimensional bar codes; that is, the reader must be aimed at each row individually. Likewise, the multiple-scan-line readers produce a number of scan lines at an angle to one another so these are not suitable for recognizing a Code 49 type of two-dimensional symbols.
In the scanning systems known in the prior art, the light beam is directed by a lens or similar optical components along a light path toward a target that includes a bar code symbol on the surface. The scanning functions by repetitively scanning the light beam in a line or series of lines across the symbol. The scanning component may either sweep the beam spot across the symbol and trace a scan line across and past the symbol, or scan the field of view of the scanner, or both.
Scanning systems also include a sensor or photodetector which functions to detect light reflected from the symbol. The photodetector is therefore positioned in the scanner or in an optical path in which it has a field of view which extends across and slightly past the symbol. A portion of the reflected light which is reflected by the symbol is detected and converted into an electrical signal, and electronic circuitry or software decodes the electrical signal into a digital representation of the data represented by the symbol that has been scanned. For example, the analog electrical signal from the photodetector may typically be converted into a pulse width modulated digital signal, with the widths corresponding to the physical widths of the bars and spaces. Such a signal is then decoded according to the specific symbology into a binary representation of the data encoded in the symbol and to the alphanumeric characters represented thereby.
The decoding process in known scanning system usually works in the following manner. The decoder receives the pulse width modulated digital signal from the scanner, and an algorithm implemented in software attempts to decode the scan. If the start and stop characters and the characters between them in the scan are decoded successfully and completely, the decoding process terminates and an indicator of a successful read (such as a green light and/or an audible beep) is provided to the user. Otherwise the decoder receives the next scan, performs another decode attempt on that scan, and so on, until a completely decoded scan is achieved or no more scans are available.
Such a signal is then decoded according to the specific symbology into a binary representation of the data encoded in the symbol, and to the alphanumeric characters so represented.
Laser scanners are not the only type of optical instrument capable of reading bar code symbols. Another type of bar code reader incorporates detectors based upon charge coupled device (CCD) technology. In such readers, the size of the detector is larger than or substantially the same as the symbol to be read. The entire symbol is flooded with light from the reader, and each CCD cell is sequentially read out to determine the presence of a bar or a space. Such readers are lightweight and easy to use, but require substantially direct contact or placement of the reader on the symbol to enable the symbol to be properly read. Such physical contact of the reader with the symbol is a preferred mode of operation for some applications, or is a matter of personal preference by the user.
Such scanning systems may comprise peripherals which are physically separate from one another, and which work together. For example, the light source and the detector may be mounted in discrete housings. A keyboard, a display, a power pack and a controller may also be mounted in separate housings. In some applications, a user must select one from among many light sources, detectors, keyboards, displays, power packs, or controllers. A system manager for the network must be apprised of exactly which of the peripherals have been selected to work together in a particular operating network.
Accordingly, it is a primary object of the present invention to establish a logical or working relationship among peripherals in a wireless local area network managed by a system manager.
In keeping with this object, one feature of this invention resides, briefly stated, in an arrangement for and a method of establishing a logical relationship among peripherals in a wireless local area network managed by a system manager. A readable identifier is associated with each peripheral. A reader for reading the identifiers is respectively associated with selected peripherals during a set-up mode of system operation. The reader has a transceiver in wireless communication with the system manager for identifying the reader and the selected peripherals to advise the system manager of the establishment of the logical relationship. In a preferred embodiment, the reader includes a radio frequency transmitter for transmitting the identifiers at radio frequency to the system manager.
In one embodiment, the identifiers are indicia having parts of different light reflectivity, such as bar code symbols, in which case, the reader includes a scanner for electro-optically reading the indicia. In another embodiment, the identifiers are radio frequency transmitters that transmit an identifying signal, in which case, the reader is a receiver for receiving the identifying signal.
The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.